Shih-Youeng Chuang

Risk factors for nonunion in patients with intracapsular femoral neck fractures treated with three cannulated screws placed in either a triangle or an inverted triangle configuration.

BACKGROUND Intracapsular femoral neck fractures are associated with high rates of nonunion. We aimed to identify risk factors for nonunion in patients with both displaced and nondisplaced intracapsular femoral neck fractures treated with three 7-mm parallel cannulated screws, placed in either a triangle or an inverted triangle configuration, using failure of fixation as the primary outcome. METHODS Clinical and radiographic data for patients with intracapsular femoral neck fractures treated with either triangle fixation (one proximal screw and two distal screws) or inverted triangle fixation (two proximal screws and one distal screw), between January 1, 2000, and July 30, 2009, were analyzed. RESULTS A total of 202 patients, seventy-six men and 126 women with an average age (and standard deviation) of 64.53 ± 15.81 years (range, nineteen to ninety-three years), were included in the analysis. Union occurred in 158 patients, and nonunion occurred in forty-four. There were no differences between the union and nonunion groups with respect to age, sex, fracture side, fracture angle, fracture level, or estimated bone density. There were significant differences in fracture type, fixation configuration, reduction quality, and screw-tip subchondral purchase between patients with and without union. The estimated odds ratio for fracture nonunion was 2.93 (95% confidence interval [CI], 1.08, 7.96) in subjects with displaced fractures compared with those without displaced fractures (p = 0.035), 18.92 (95% CI, 1.91, 187.09) in subjects with borderline and unacceptable reduction compared with those with anatomic reduction (p = 0.012), and 2.92 (95% CI, 1.27, 6.69) for internal fixation with a triangle configuration compared with fixation with an inverted triangle configuration (p = 0.010). CONCLUSIONS Screw fixation with a triangle configuration, a displaced fracture, and poor reduction are risk factors for nonunion in intracapsular femoral neck fractures treated with fixation with multiple screws.

Exogenous Cross-linking Increases the Stability of Spinal Motion Segments

Study Design. The mechanical stability of cross-linked and control spinal motion segments was evaluated using neutral zone, range of motion (ROM), and instability score metrics. Objective. To determine if exogenous cross-linking could increase the stability of spinal motion segments. Summary of Background Data. The microstructure of the anulus fibrosus extracellular matrix can affect the stability of the intervertebral joint. Parallel testing in our laboratory has shown that exogenous cross-linking can improve the fatigue resistance of anulus fibrosus. Methods. There were 3 separate experimental protocols conducted. The first study used calf lumbar intervertebral joints randomly divided into a genipin cross-linked group and phosphate buffered saline-soaked controls. After 2 days of soaking, flexion-extension ramp cycles were applied to the specimens. The second study repeated the test protocol using 22 moderately and severely degenerated human lumbar intervertebral joints. The third experiment compared the effect of cross-linking treatment on human discs with known degrees of preexisting mechanical instability. Each data set was used to assess joint instability by 3 calculations: ROM, neutral zone, and an instability score. Joint instability for each data set was evaluated using 3 calculations: ROM, neutral zone, and a novel instability score. Results. These results show that cross-link augmentation can effectively reduce instability of intervertebral discs. The stabilizing effect was observed to be higher in the more mechanically unstable discs. However, cross-linking did not appear to affect the total range of sagittal motion. Conclusions. By reducing the neutral zone, exogenous cross-linking may help combat the progression of instability in degenerative disc disease.

Osteoid osteoma in the talar neck: a report of two cases.

This article describes two cases of juxta-articular osteoid osteoma of talar neck. Both patients were initially treated as having ankle sprains or arthritis before diagnosis of osteoid osteoma. A high index of suspicion and appropriate imaging studies are important to make an early diagnosis of this disorder. Once diagnosis is confirmed, en bloc resection and autogenous bone graft can cure the disorder.

Exogenous crosslinking recovers the functional integrity of intervertebral disc secondary to a stab injury

Exogenous crosslinking was proved to improve the fatigue resistance of anulus fibrosus and the stability of motion segment. The effect of crosslinking on the recovery of stab-injured discs, however, was less studied. The purpose of this study is to find if the exogenous crosslinking can increase the mechanical function of injured discs. Fresh healthy porcine discs (T2/T9) from 6-month-old swine were obtained immediately following death. Anular puncture using 16 and 18 G spinal needle were used to create medium and large disc stab injury models. Three treatments were designed for each injury model. The first one is the injured discs without treatment. The second one is the injured discs soaked with phosphate buffered solution for 2 days. The third one is the injured discs soaked with 0.33% genipin solution for 2 days. The disc integrity was evaluated using quantitative discomanometry (QD) apparatus. Four QD parameters, that is, the leakage pressure and volume, and the saturate pressure and volume, were analyzed to find the efficacy of treatment. We found that soaking of genipin solution recovered the disc leakage pressure from 1.3 to 1.8 MPa in 16 G-injury-model and from 2.3 to 3.2 MPa in 18 G-injury-model, and recovered the saturate pressure from 1.6 to 2.0 MPa in 16 G-injury-model and from 2.7 to 3.7 MPa in 18 G-injury-model. The improvement of disc integrity by soaking with genipin solution indicate that the exogenous crosslinking may help the biomechanical performance of an injured disc.

Results of infected total knee arthroplasty treated with arthroscopic debridement and continuous antibiotic irrigation system

Background: Arthroscopic debridement with continuous irrigation system was used with success in treating infective arthritis. We evaluated the effectiveness of arthroscopic debridement coupled with antibiotic continuous irrigation system in acute presentation of late infected total knee arthroplasty. Materials and Methods: We performed a retrospective review of medical record of patients with acute presentation of late infected total knee arthroplasty who were treated by arthroscopic debridement coupled with continuous postoperative antibiotic irrigation system. Results: Seventeen patients were included in our study. 15 (88%) patients preserved their total knee prosthesis at mean of followup of 27.5 months (range, 14-28 months). Two (12%) patients failed arthroscopic protocol and finally needed two stages revision. Our study showed an 88% prosthesis retention rate in patients with acute presentation of late prosthetic knee infection. No complication was associated with use of antibiotic irrigation system. Conclusion: Arthroscopic debridement combined with continuous antibiotic irrigation and suction is an effective treatment for patients with acute presentation of late infected total knee arthroplasty.

Exogenous Crosslinking Restores Intradiscal Pressure of Injured Porcine Intervertebral Discs: An In Vivo Examination Using Quantitative Discomanometry.

Study Design. In vivo examination of intradiscal pressure by quantitative discomanometry (QD). Objective. To determine whether an injectable, exogenous crosslinking could acutely restore intradiscal pressure of stab-injured discs in vivo by short-term treatment. Summary of Background Data. Disc biomechanical performance depends on its integrity associated with the intradiscal pressure and mechanical properties. Genipin crosslink augmentation has demonstrated the in vitro biomechanical capability to improve intervertebral joint stability and increase mechanical properties of the annulus fibrosus. Methods. 4 lumbar discs on each of 8 swine were randomly assigned to 4 groups: intact, injured, untreated, and crosslinked. A 16G needle was stabbed into the annulus fibrosus to create the disc injury model. An injection of 0.33% genipin solution was delivered into the annulus to treat the injury. QD technique was performed to examine the intradiscal pressure for the intact and injured discs at the time of surgery, while untreated and crosslinked discs were measured 1-week postsurgery. 4 QD parameters were analyzed and compared across the 4 groups: leakage pressure and volume, and saturation pressure and volume. Results. The leakage and saturation pressures of the injured group were significantly lower than those of the intact group (P = 0.004 and P = 0.01, respectively). The leakage and saturation pressures of untreated discs were statistically equivalent to the injured levels, but with a 2-times higher saturation volume. Relative to the untreated group, the leakage pressure and saturation pressure of genipin-crosslinked discs had a 617% (P = 0.008) and a 473% increase (P = 0.007), respectively. Conclusion. A large disc injury produced by annular puncture immediately lowered intradiscal pressure when left untreated. Genipin crosslinking can restore intradiscal pressure acutely in vivo without any obvious morbidity associated with the injection. Level of Evidence: N/A

Effects of Collagen Crosslink Augmentation on Mechanism of Compressive Load Sharing in Intervertebral Discs

Exogenous crosslinking has been shown to have potential for treating disc degeneration and back pain due to its ability to increase the strength and toughness of the annulus fibrosus, increase intervertebral joint stability, decrease intradiscal pressure, and increase fluid flow through the disc. Some results imply that crosslink augmentation may also lead to changes in the compressive load sharing properties of the disc. The objective of the present study was to evaluate directional stress distribution changes of the disc following genipin crosslinking treatment. Bovine lumbar motion segments were randomly divided into control and crosslinked groups. Annular strains were determined from simultaneous deformation measurements at various time points during compressive creep testing. Four stress components of the annulus were then calculated according to the previously measured modulus data. Immediately after the application of a 750-N compressive load, mean axial and radial compressive stresses in the crosslinked group were twofold higher than control means. Conversely, mean lamellae-aligned and circumferential tensile stresses of the crosslinked discs were 8- and threefold lower, respectively, compared to control means. After 1-h creep loading, the two compressive mean stresses in both the control and genipin-crosslinked specimens increased approximately threefold from their initial 750-N-loaded values. The two tensile mean stresses in the crosslinked group remained lower than the respective levels of the control means after creep loading. A greater proportion of annular compressive load support under compressive creep loading, with a commensurate decrease in both tensile stresses and strains, was seen in the discs following exogenous crosslink augmentation.

Analysis of Intervertebral Disc Degeneration with Nondestructive Indentation Test: Analyses in Time and Frequency Domains

Background: The objective of this study was to develop a nondestructive indentation technique to quantify the degradation of the material properties of the annulus fibrosus (AF) resulting from nontraumatic cyclic fatigue and to analyze the data in both the time domain, with the relaxation ratio, and the frequency domain, with a parametric autoregressive model. Methods: In this study, 7 human cadaver intervertebral discs were included (4 from L3/4, 3 from L2/3) with a mean age of 52 years (range, 35-61). The relaxation indentation test was applied with an MTS 858 materials testing system using 2.5 mm hemispherical indenters on the posterior disc. Computational analyses, separated into time and frequency domains, were undertaken with an IBM-compatible computer using custom-designed software based on the Matlab (Mathworks, Natik, MA) programming environment. Results: In the time domain, the relaxation ratio averaged 60.7% in the control and 74.4% after cycling. There was a 13.7% increase after cycling. In the frequency domain, the best order of the relaxation function data was one in all specimens. The equation for the specimens was: y(n)-(0.99835±0.0035)×y(n-1)=e(n), where e(n) is white noise. Conclusion: In our hypothesis, the degeneration of the disc arises mainly, in the first step, from mechanical changes in the AF after mechanical loading, followed by an induced sequence of mechanical and biological changes. Microtrauma of the AF because of repetitive or sustained loading will cause plastic deformation of the AF, leading to a vicious cycle of disc degeneration.